The present invention relates to a modification to foot supports for railroad rails that are used in track systems (rails and switches), this being arranged in the vicinity of rail-securing devices on ties or similar track-holding elements. In this connection, a sole plate or a ribbed plate, respectively, a slide chair plate or the like, or simply a shim can be provided, the sole plate or ribbed plate, slide chair plate or shim this lying on the top of the tie or the like and being secured to the by means of coach bolts or the like.
The railroad rails that are used for track construction are designed as so-called wide bottom flange rails that are of a modified T cross-section, the rail head being of a mushroom-shaped cross-section. Such wide-bottom flange rails are known, for example, by the designations UIC54 or UIC60, respectively, as well as S 49 or S 54 shapes, etc., and have a cross-section that is symmetrical about their vertical axis y--y. The axis of symmetry y--y is perpendicular to the centroidal axis x--x of a wide-bottom flange rail. The centroidal axis x--x is located at a considerable distance (approximately 10 mm) beneath the half total height of the rail cross-section. These wide-bottom flange rails are rolled with the Y-axis horizontal. This method, used to roll the wide-bottom flange rails--which is governed by the configuration of the profile--results of necessity in the fact that their (underside) foot support area undergoes a slightly convex-crowned shaping towards the vertical axis y--y. Because of this, in contrast to a horizontal ideal plane, the rail foot supporting surface has a crown in the area of the vertical axis y--y, and this can amount to 0.2 and 0.4 mm. It is difficult and unusual to eliminate this crown by way of alignment.
Because of this crowning of its foot support surfaces, which is caused by rolling technology, the wide-bottom flange rails that are used in track systems stand in a way that is mechanically unstable on the associated sole plates or on the shims, respectively, e.g., in the case of concrete ties, or on ribbed plates.
This unstable rail position is particularly critical if the supporting surfaces, in the case of ribbed plates on wooden ties, for example, is not flat but rather deformed in a more or less convex shape that is opposite to the crowning of the rail foot supporting surface, for then, for all practical purposes, two oppositely curved surfaces are in contact only on a line that extends along a common apex. Since both the convexity of the rail foot supporting surface as well as that of the supporting surface on the sole plate that faces towards this result in a crown, it is impossible to achieve an exact and stable starting position for bracing the rail feet by means of a rail attachment device. For this reason, when the rail attachment device is tightened, their vertical axis of symmetry y--y can tip either inwards or outwards by an amount that depends on the crowning, and this can lead to a reduction or enlargement of the cross-rail distance (track) in the rail section or in switches.
The crowning that occurs in the rail foot supporting surface and the sole plate leads to a further disadvantage in that--particularly in the case of interior curve or exterior curve switches that are subjected to heavy loads--the edges of the rail foot sink into the inner bearing surface of the outer ribs of the sole plates that are used very rapidly and very deep, as a result of the tilting movements that are caused by the unstable position of the rails. This fact leads not only to an uncontrolled and thus hazardous widening of the track width in the track, but also to the fact that the ribbed plates, and in particular the ribbed sliding chair plates, become unserviceable very quickly and thus have to be replaced, sometimes after they have been installed for only a short time.
A further disadvantage that occurs as a result of convex supporting surfaces is that the rails can move sideways as a result of forces applied by the wheels. The rotation of the rail head that is caused by this changes the geometry of the line of contact between the wheel and the rail. The rolling characteristics of rolling stock can be affected very adversely because of this, particularly at high speeds.
In consideration of the disadvantages described above, which result from the use of railroad rails that are rolled when horizontal and used for track construction, it is the task of the present invention to create a modification for the foot supports for railroad rails with the typical characteristics described in the introduction hereto, and which, using simple means and, for all practical purposes, with no extra cost ensure a stable positioning of railroad rails relative to the other functional elements of track systems and switches, particularly in the vicinity of the rail attachment points on ties or corresponding track-securing elements.